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R. rickettsii is an obligate intracellular alpha proteobacterium that belongs to the Rickettsiaceae family. [6] Within the Rickettsia species, these bacteria are divided into four clades. The clades include ancestral group, spotted fever group (SFG), typhus group, and transitional group.
As with other bacterium transmitted via ticks, the process generally requires a period of attachment of 4 to 6 hours. However, in some cases a Rickettsia rickettsii infection has been contracted by contact with tick tissues or fluids. [19] Then, the bacteria induce their internalization into host cells via a receptor-mediated invasion mechanism.
Rickettsialpox - caused by Rickettsia akari, this disease is transmitted by mite bites and is generally milder than other rickettsial infections. Rocky Mountain spotted fever - caused by Rickettsia rickettsii, this disease is transmitted by tick bites and is prevalent in the Americas.
Rickettsia is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long).
In the past, rickettsioses were considered to be caused by species of Rickettsia. [2] However, scrub typhus is still considered a rickettsiosis, even though the causative organism has been reclassified from Rickettsia tsutsugamushi to Orientia tsutsugamushi .
They are obligate intracellular parasites, and some are notable pathogens, including Rickettsia, which causes a variety of diseases in humans, and Ehrlichia, which causes diseases in livestock. Another genus of well-known Rickettsiales is the Wolbachia , which infect about two-thirds of all arthropods and nearly all filarial nematodes. [ 2 ]
The Rickettsiaceae are a family of bacteria. The genus Rickettsia is the most prominent genus within the family. The bacteria that eventually formed the mitochondrion (an organelle in eukaryotic cells) is believed to have originated from this family. Most human pathogens in this family are in genus Rickettsia.
Hosts usually come into contact with the bacteria through the skin, but there are chances of contracting the bacteria from a bite, such as that of ticks, mites, and/or mosquitoes (Rickettsia rickettsii). [5] Listeria monocytogenes is found in soil, water, and also decaying animals and plants.